Design study of superconducting magnets for tokamak experimental fusion reactor, (2)

Design study has been made of superconducting magnet system for JAERI Experimental Fusion Reactor (JXFR) of tokamak type. The system is composed of superconducting toroidal and poloidal coils, cryostat, mechanical support and cooling system. Described in this report are analysis of magnetic flux density and electromagnetic force distributions, structure analysis by finite element method, seismic analysis, and analysis of heat generation such as AC loss in superconductor, eddy current loss in structural members and heat inleak. Following is the design. (1) Plasma specifications: power 125MW, major radius 6.75m, minor-radius 1.5m, and plasma current 4.4MA. (2) Toroidal coils: D shape, number of coils 16, total magnetomotive force 186 MAT, magnetic flux density at plasma center 5.5T, and maximum magnetic flux density at coil winding 11.0T. (3) Poloidal coils: number of coils 28, total magnetomotive force 47.8MAT for transformer coils and 16.6MAT for vertical field coils, radiuses 2.0 - 12.6m and maximum magnetic field at coil winding 5.6T. (4) Nb3Sn and NbTi superconducting materials for toroidal coils and poloidal coils respectively. (5) Pool boiling for cooling superconductors of toroidal and poloidal coils because of simplicity of the cooling system. (6) Support system consisting of intermediate pipe between toroidal and poloidal coils, support rings between poloidal coils of small radiuses, central column and central-column bottom structure. (7) Superconducting cables for toroidal and poloidal coils, reinforced by stainless steel, to obtain sufficient mechanical strength to support the huge electromagnetic hoop force. (author)